From the NPS FAQs:
"How can I receive information about the park - maps, books, brochures, trip planning...?
We are happy to mail information to you - but before you request a packet, please explore the website. The website will answer the vast majority of your questions. If you wish to receive a mailing, please contact park or email the park with your name and address information."https://www.nps.gov/isro/contacts.htm